Their conversion to dairy is the seventh in the Waimarino during the past 10 years.
The Hammonds' marathon effort started in October last year, when son Mike and his partner, Aniwa Mills, wanted to return and work the family farm. They arrived in May.
Mike will be the fourth generation to milk cows on the property. During his last season milking in Reporoa, his herd didn't have a single grading for unacceptable milk, and he's likely to maintain that high standard.
"I'm proud to be able to let the fourth generation have a go," his father said.
Horizons Regional Council deemed the changes on the farm an intensification, even though the land is now carrying fewer stock.
Getting consent to convert to dairying required a 98-page nutrient management plan, prepared by consultants.
Under their consent, the Hammonds can leach 26kg of nitrate per hectare per year, measured by the Overseer computer model.
They are expected to feed their herd of 200 on grass, hay, silage and crops grown on their own land, with a measured meal feed for each cow as needed at milking time.
"We wouldn't want to graze any more anyway. We're looking at fewer cows but with higher production," Mr Hammond said.
They will be allowed to increase the amount of nitrogen leached to 29kg if they can prove that level is reached by feeding the cows on grass grown on the land.
They have installed an 1800cu m effluent pond, sized to store effluent washed out of their new dairy shed for 105 days. They have consent to apply the effluent to parts of the farm that are away from streams, houses and roads.
Using it will reduce the amount of fertiliser needed and be "hugely beneficial", Mr Hammond says.
They are required to use water from the top of the effluent pond to wash down the milking shed, to reduce their overall water take.
It's currently from surface water, but they will investigate sinking a bore. Because their current take is less than 30,000cu m per day, it does not require consent.
The concept of staying within the carrying capacity of the land is one Mr Hammond believes in, but he said the extreme way Horizons enforced it wasn't always pleasant.
One of the set-up costs was shares in Fonterra, the only company collecting milk in the Waimarino. And the Hammonds also changed the lines company supplying their electricity to Powerco, which has resulted in huge savings.
They demolished an old milking shed and put up a new 30-a-side herringbone one that required 200cu m of concrete. It's all fitted out with modern machinery. Mrs Hammond even gets a breakdown on the quality of the previous day's milk on her smart phone every day.
The size of their Ruaview farm has grown from 120ha to 140ha with the purchase of 20ha on the other side of the Raetihi-Ohakune Rd. They had to build a $120,000 underpass under the road. Ruapehu District Council and the New Zealand Transport Agency contributed to the cost, because the road has more than 500 vehicles a day.
They are also about to build a silo, to house the meal measured out to cows at milking time.
A stand-off pad is planned, for the animals to be fed on in bad weather. At the moment, they're using a "sacrificial paddock" instead, and will crop it later.
Much later there, they are likely to build a herd home of some kind. There are none in the Waimarino so far.
The herd they chose was a Friesian one from Tokoroa, with cows averaging 420kg of milk solids each a year. They aim to get that up to 500kg a year.
It will only take an hour to milk the 200 twice a day, making for a good lifestyle - once calving is over and all the systems are working.
Calving is an intensive time, Mr Hammond says, and the Hammonds' calves have been sold to a neighbour. "It's a huge commitment. You have the responsibility for a lot of animals health and well-being but it sets up your production for the year."